Scientists Find Two 'Wild' Stars in Extremely Fast Orbit
2022-10-16
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1Unlike the sun, about half of the stars in our Milky Way galaxy orbit another star in what is known as a binary system.
2The word "binary" means two.
3Researchers recently described an unusual binary system in the science publication Nature.
4The two stars orbit each other every 51 minutes in one of the fastest orbital periods known for a rare kind of binary system.
5The two stars are about 3,000 light years from Earth.
6One light year is the distance light travels in a year.
7The system belongs to a kind of binary star known as cataclysmic variable.
8That term describes a star system that can brighten by as much as 10,000 times for short periods.
9The unusual system includes a star similar to our sun orbiting very closely to what is called a white dwarf.
10A white dwarf is the hot and dense center of a burned out star.
11Over billions of years, the distance between the two stars has decreased so much that they are now closer than the moon is to Earth.
12Massachusetts Institute of Technology space scientist Kevin Burdge was lead writer of the study.
13He said, "Imagine if the moon zipped across the sky 10 times a night. That's the kind of speed we are talking about."
14Because of the small distance between them, the white dwarf is taking material from the larger star.
15The larger star is about the same temperature as the sun but it is now only the size of Jupiter, the largest planet in our solar system.
16The white dwarf has a mass equal to 56 percent of our own sun.
17It is extremely dense, however, because it is only 1.5 times the Earth's width.
18Burdge said, "...when stars die of old age they become white dwarfs - but then this remnant began to eat its companion."
19Burdge added that the white dwarf interrupted the normal development of the first star.
20He said the stars have been orbiting each other for 8 billion years.
21The researchers used data from the Palomar Observatory in California and from telescopes in Hawaii and in the Canary Islands.
22Stars are mostly made up of hydrogen, with smaller amounts of helium and other elements.
23In this system, the larger of the two stars has an unusually large amount of helium.
24Scientists say it lost hydrogen from its outer layers to the smaller white dwarf.
25At the same time, its hot center continues to make helium from existing hydrogen through the process of nuclear fusion.
26The binary system periodically brightens by a huge amount partly because the larger star is being pulled out of its normal shape by the white dwarf's gravity.
27There are more than a thousand known cataclysmic variables. Only 12 or so have orbital periods below 75 minutes.
28While the binary system's 51 minutes is quick, it is not the record when compared to other kinds of binaries.
29The fastest known orbital period among binary stars is just five minutes and 21 seconds.
30"There is tons of wild stuff going on in space," noted Burdge.
31I'm Gregory Stachel.
1Unlike the sun, about half of the stars in our Milky Way galaxy orbit another star in what is known as a binary system. The word "binary" means two. 2Researchers recently described an unusual binary system in the science publication Nature. The two stars orbit each other every 51 minutes in one of the fastest orbital periods known for a rare kind of binary system. 3The two stars are about 3,000 light years from Earth. One light year is the distance light travels in a year. 4The system belongs to a kind of binary star known as cataclysmic variable. That term describes a star system that can brighten by as much as 10,000 times for short periods. 5The unusual system includes a star similar to our sun orbiting very closely to what is called a white dwarf. A white dwarf is the hot and dense center of a burned out star. 6Over billions of years, the distance between the two stars has decreased so much that they are now closer than the moon is to Earth. 7Massachusetts Institute of Technology space scientist Kevin Burdge was lead writer of the study. He said, "Imagine if the moon zipped across the sky 10 times a night. That's the kind of speed we are talking about." 8Because of the small distance between them, the white dwarf is taking material from the larger star. 9The larger star is about the same temperature as the sun but it is now only the size of Jupiter, the largest planet in our solar system. The white dwarf has a mass equal to 56 percent of our own sun. It is extremely dense, however, because it is only 1.5 times the Earth's width. 10Burdge said, "...when stars die of old age they become white dwarfs - but then this remnant began to eat its companion." 11Burdge added that the white dwarf interrupted the normal development of the first star. He said the stars have been orbiting each other for 8 billion years. 12The researchers used data from the Palomar Observatory in California and from telescopes in Hawaii and in the Canary Islands. 13Stars are mostly made up of hydrogen, with smaller amounts of helium and other elements. In this system, the larger of the two stars has an unusually large amount of helium. Scientists say it lost hydrogen from its outer layers to the smaller white dwarf. At the same time, its hot center continues to make helium from existing hydrogen through the process of nuclear fusion. 14The binary system periodically brightens by a huge amount partly because the larger star is being pulled out of its normal shape by the white dwarf's gravity. 15There are more than a thousand known cataclysmic variables. Only 12 or so have orbital periods below 75 minutes. While the binary system's 51 minutes is quick, it is not the record when compared to other kinds of binaries. 16The fastest known orbital period among binary stars is just five minutes and 21 seconds. 17"There is tons of wild stuff going on in space," noted Burdge. 18I'm Gregory Stachel. 19Will Dunham reported this story for Reuters. Gregory Stachel adapted it for VOA Learning English. 20_______________________________________________________________________ 21Words in This Story 22galaxy - n. any one of the very large groups of stars that make up the universe 23burned out -v. (phrasal) to be burned or used up 24zip - v. to move or act very quickly 25remnant - n. the part of something that is left when the other parts are gone 26companion -n. one of at least two stars orbiting in a binary or multiple star system 27interrupt - v. to cause (something) to not be even or continuous 28layer - n. an amount of something that is spread over an area 29______________________________________________________________________ 30What do you think of the stars? 31We want to hear from you. We have a new comment system. Here is how it works: 32Each time you return to comment on the Learning English site, you can use your account and see your comments and replies to them. Our comment policy is here.